I am easing into it. It's a tough switch because I am very familiar with version 5.
I think that in the next few months I will have made the big switch but SKS 5 works for just fine for me. If and when I get Vista will be the big reason for me to switch. I got suckered on Windows ME, I'm not in any hurry to repeat that wonderful series of events.
The interface is far superior than earlier versions. It will take some time but it will breed a new generation of Skinners. I think that from a beginner's perspective. the new interface is easier to understand and use.
Knowing the limits of XP/Vista and graphics will take new skinnner's time. Unless you guys have added an "increase talent" button of course.

I did have a huge hiccup with SKS 6 that cause me to sort of write it off until full release. I opened a skin I was working on in SKS 6,.... didn't really do too much, closed it. Next time I opened the skin in SKS5 my title bar buttons were gone. Nowhere to be found. Not in the file anymore...gone. I wasn't working on any buttons at the time. Just text colors. It turned out to be a blessing in disguise as the new buttons I had to make were way better than the originals. LOL I am pretty sure it was SKS6 that deleted the files but user error is ceertainly not out of the question.
I think that SKS6 will be very popular with people that were intimidated by SKS 5 or earlier. I know I will favor it at some point. I haven't seen a tutorial yet but that always helps.